Method and apparatus for printing an image onto a 3-dimensional surface

ABSTRACT

A printing apparatus ( 1 ) for printing an image onto a 3-dimensional surface of a plastics article such as a mobile telephone or computer mouse (not shown) has a housing ( 2 ) having a slot ( 3 ) for receiving a drawer ( 4 ) for receiving one of more of the articles to be printed. The drawer ( 4 ) is provided with clamp release buttons ( 5 ) on a front surface ( 6 ) thereof. The housing ( 2 ) contains a heater box ( 7 ), located above the slot ( 3 ), and having a fan ( 8 ) for directing hot air through a separator plate ( 9 ) onto a transfer element (not shown) mounted on the top of drawer ( 4 ) over the article on which an image is to be printed. The transfer element has a support layer of met,allised amorphous polyethylene terephthalate (APET) having an aqueous coating of polyvinyl polymers, which may also contain synthetic silica, surfactants and optical brightening agents. The metallisation is formed by applying one or more metallic coatings to one side of the APET film during manufacture. The heater box ( 7 ) is provided with a heater (not shown) which is controlled by means of an electrical enclosure ( 10 ) containing a programmable logic controller (PLC) and heating controller.

The present invention relates to a method and apparatus for printing animage onto a 3-dimensional surface, and relates particularly, but notexclusively, to a method and apparatus for printing an image onto anarticle of plastics material having a protective coating thereon.

A method of printing an image onto a 3-dimensional surface of a plasticsarticle such as a mobile telephone is disclosed in our internationalpatent application WO 01/96123. In this method, a transfer elementcarrying an image is heated to make it more flexible, and the heatedtransfer element is applied by means of vacuum forming to the3-dimensional surface with substantially uniform pressure across thearea of contact. The transfer element is then heated to at leastpartially transfer the image from the transfer element to the3-dimensional surface.

Plastics articles onto which images have been printed are often providedwith protective gloss coatings to avoid scratching or other degradationof the image. Such gloss coatings are generally applied to the article,subsequently to the image printing process, by means of chemicalspraying of the gloss coating. As a result of the often hazardous natureof chemicals used in the formation of the gloss coating, the knownprinting process suffers from the drawback that the gloss coating mustbe applied by skilled personnel using specialist facilities. This inturn causes the drawback that although the image printing process can becarried out by persons relatively unskilled in printing, the printedarticle must be returned subsequently to printing to specialist premisesfor application of the gloss coating. This significantly increases thecost of production of printed articles using the known process.

Preferred embodiments of the present invention seek to overcome theabove disadvantages of the prior art.

According to an aspect of the present invention, there is provided amethod of printing an image onto a 3-dimensional surface, the methodcomprising:

heating a transfer element having an image printed thereon to make thetransfer element more flexible;

applying the heated transfer element to a 3-dimensional surface having aprotective coating thereon, with substantially uniform pressure acrossthe area of contact between the transfer element and the surface, suchthat the image faces the surface; and

heating the transfer element to at least partially transfer the imageinto the protective coating.

By at least partially transferring the image into or through theprotective coating, this provides the advantage that the protectivecoating can be applied prior to the printing step. As a result, theprinting step can be carried out by persons who are relatively unskilledin printing, subsequently to application of the protective coating at alocation having specialist equipment, without the need to subsequentlytransport printed articles to the specialist location for application ofthe protective coating. This in turn provides the advantage of reducingthe cost of production of printed articles using the method, as well assignificantly increasing the range of applications of the method.

The method may further comprise the step of applying said protectivecoating.

The method may further comprise the step of applying a receptor coatingprior to application of said protective coating.

This provides the advantage of enabling better adhesion of an image tothe surface to be printed, and the receptor coating can be applied atthe same specialist location used to apply the protective coating, andby means of similar, or the same, apparatus as that used to apply theprotective coating.

The method may further comprise the step of printing an image onto saidtransfer element.

The image may be printed by means of a digital printer.

This provides the advantage of enabling customised images to be printedonto the surface, for example by means of data on a user's computer sentto the digital printer.

The transfer element may be applied to the surface by means of vacuumforming.

This provides the advantage of enabling the transfer element to beeasily applied to the surface with substantially uniform pressure acrossthe area of contact between the transfer element and the surface.

The transfer element may be at least partially heated by means of hotgas.

This provides the advantage of enabling more uniform and efficientheating than in the prior art, and avoiding shadows which wouldotherwise occur if a source of radiant heat were to be used.

The method may further comprise the step of applying a thermallyconductive film to the transfer element.

This provides the advantage of improving the heat resistance and thermalforming properties of the transfer element.

The method may further comprise a step of removing solvent and/ormoisture from a region adjacent said transfer element during heatingthereof.

This provides the advantage of minimising the occurrence of bubblesbetween the protective coating and the transfer element.

According to another aspect of the invention, there is provided anapparatus for printing an image onto a 3-dimensional surface, theapparatus comprising:

fixing means for fixing a transfer element, having an image printedthereon, in position relative to a 3-dimensional surface on which animage is to be printed and having a protective coating applied thereto;

heating means for heating the transfer element to make it more flexibleand to at least partially transfer the image into the protectivecoating; and

application means for applying the flexible transfer element to thesurface with substantially uniform pressure across the area of contactbetween the transfer element and the surface such that the image facesthe surface.

By providing fixing means for fixing the transfer element in positionrelative to the surface, this provides the advantage of enabling theimage to be reliably and accurately located on the surface. This in turnenables the printing operation to be carried out by persons relativelyunskilled in printing, which in turn increases the range of applicationsof the printing process.

The fixing means may comprise at least one recess for receiving at leastone part having a respective 3-dimensional surface, and for fixing arespective transfer element relative to the or each said part.

The recess may be at least partially removable from a housing of theapparatus, and the fixing means may be adapted to fix the transferelement in response to insertion of the recess into the housing.

This provides the advantage of making the apparatus easier to use, as aresult of which images can be printed onto 3-dimensional surfaces bymeans of non-specialist personnel.

The apparatus may comprise further fixing means for holding the or eachsaid recess in position in the housing.

The apparatus may further comprise control means for actuating theheating means and/or the application means in response to insertion ofthe recess into the housing.

The heating means may be adapted to direct hot gas towards the surface.

This provides the advantage of enabling more efficient and uniformheating of the surface than in the case of the prior art.

The apparatus may further comprise moisture and/or solvent removingmeans for removing solvent and/or moisture from a region adjacent thetransfer element.

This provides the advantage of minimising the occurrence of bubblesbetween the protective coating and the transfer element.

The application means may comprise vacuum forming means.

This provides the advantage of enabling the transfer element to beconveniently applied to the surface with substantially uniform pressureacross the area of contact.

According to a further aspect of the present invention, there isprovided a transfer element adapted to have an image printed thereon,the transfer element comprising:

a carrier layer adapted to be heated to make the carrier layer moreflexible;

an image supporting layer; and

a thermally conducting layer.

By providing a thermally conducting layer, this provides the advantageof improving the heat resistance and thermal forming properties of thetransfer element.

A preferred embodiment of the present invention will now be described,by way of example only and not in any limitative sense, with referenceto the accompanying drawings, in which:—

FIG. 1 is a perspective view of a printing apparatus embodying thepresent invention and with a product receiving drawer thereof in an opencondition;

FIG. 2 is a schematic perspective view of the apparatus of FIG. 1 withthe product receiving drawer thereof in a closed condition and showinginternal components of the apparatus;

FIG. 3 is a partially cut away perspective view of a circulating fan andseparator plate of the apparatus of FIGS. 1 and 2;

FIG. 4 is a perspective view of the apparatus of FIG. 1 with the productreceiving drawer in a closed condition; and

FIG. 5 is a detailed, partially cut away view of the product receivingdrawer of the apparatus of FIG. 1.

Referring to FIGS. 1 and 2, a printing apparatus 1 for printing an imageonto a 3-dimensional surface of a plastics article such as a mobiletelephone or computer mouse (not shown) has a housing 2 having a slot 3for receiving a drawer 4 for receiving one of more of the articles to beprinted. The drawer 4 is provided with clamp release buttons 5 on afront surface 6 thereof, the function of which will be described ingreater detail below.

As shown more clearly in FIG. 2, the housing 2 contains a heater box 7,located above the slot 3, and having a fan 8 for directing hot airthrough a separator plate 9 onto a transfer element (not shown) mountedon the top of drawer 4 over the article on which an image is to beprinted. The transfer element has a support layer of metallisedamorphous polyethylene terephthalate (APET) having an aqueous coating ofpolyvinyl polymers, which may also contain synthetic silica, surfactantsand optical brightening agents. The metallisation is formed by applyingone or more metallic coatings to one side of the APET film duringmanufacture. The heater box 7 is provided with a heater (not shown)which is controlled by means of an electrical enclosure 10 containing aprogrammable logic controller (PLC) and heating controller.

The drawer 4 is slidably mounted in the slot 3 by means of slides 11 andis held in position in the slot 3 during the printing operation by meansof a solenoid 12. A vacuum pump 13 is also provided in the housing forvacuum forming the transfer element onto the article to be printed andfor removing moisture and/or solvent from the air around the transferelement, the purpose of which will be described in greater detail below.

Referring to FIG. 3, the heater box 7 defines a heater chamber 14 whichdirects hot air through separator plate 9 towards the drawer 4. Thedrawer 4 defines a vacuum chamber below the heater chamber 14, thetemperature of the vacuum chamber being maintained generally constant bymeans of a fan 15 (FIG. 2) located outside of the heater chamber 14. Thesolenoid 12 is controlled by means of a drawer release catch 16 (FIG.4).

Referring to FIG. 5, the drawer 4 has a component mould mount block 17for receiving a mould (not shown) on which an article of plasticsmaterial having a 3-dimensional surface to be printed with an image ismounted. The mould mount block 17 is located at the bottom of a recess18 for receiving the plastics article, and a film clamp frame 19 ishinged to the rear side 20 of drawer 4 to enable a suitably shapedtransfer element printed with an image (not shown) to be immovablyclamped to the top of the drawer 4.

The operation of the apparatus shown in FIGS. 1 to 5 will now bedescribed.

In order to print an image onto a 3-dimensional surface of a plasticsarticle, the article is first provided with an optional receptorcoating, and is then provided with a gloss protective coating, by meansof chemical spraying at a specialist spraying facility remote from thelocation of the apparatus 1. The transfer element (not shown) comprisesa film of plastics material having a metallised coating and having animage printed thereon by means of a conventional digital printer. Theimage can be printed onto the transfer element by the same person asoperates the apparatus 1 for printing the image onto the 3-dimensionalsurface of the plastics article.

The plastics article is located in recess 18 in drawer 4, and thetransfer element rigidly clamped to the top of drawer 4 by means ofclamp frame 19 such that the coating printed with the image facestowards the plastics article. The drawer 4 is then pushed into the slot3 and the apparatus actuated. Hot air is initially directed towards thetransfer element to heat it and make it more flexible, and the transferelement is then vacuum formed by means of vacuum pump 13 onto the3-dimensional surface. Further heat is then directed by means of fan 8onto the transfer element, which causes the image to be at leastpartially transferred into or through the protective coating on theplastics article. The vacuum pump 13 also removes moisture and/orsolvent from the air around the article to minimise the formation ofbubbles between the protective coating and the transfer element.

When the printing process is completed, the manual drawer release 16 isdepressed to allow the drawer 4 to be removed from the slot 3 and theprinted product to cool. The deformed transfer element is then removedfrom the article, which has the image printed through its glossprotective coating, and which is therefore protected by the glosscoating from scratching and other degradation.

It will be appreciated by persons skilled in the art that the aboveembodiment has been described by way of example only, and not in anylimitative sense, and that various alterations and modifications arepossible without departure from the scope of the invention as defined bythe appended claims.

1. A method of printing an image onto a 3-dimensional surface, themethod comprising: heating a transfer element having an image printedthereon to make the transfer element more flexible; applying the heatedtransfer element to a 3-dimensional surface having a protective coatingthereon, with substantially uniform pressure across the area of contactbetween the transfer element and the surface, such that the image facesthe surface; and heating the transfer element to at least partiallytransfer the image into the protective coating.
 2. A method according toclaim 1, further comprising the step of applying said protectivecoating.
 3. A method according to claim 2, further comprising the stepof applying a receptor coating prior to application of said protectivecoating.
 4. A method according to claim 1, further comprising the stepof printing an image onto said transfer element.
 5. A method accordingto claim 4, wherein the image is printed by means of a digital printer.6. A method according to claim 1, wherein the transfer element isapplied to the surface by means of vacuum forming.
 7. A method accordingto claim 1, wherein the transfer element is at least partially heated bymeans of hot gas.
 8. A method according to claim 1, further comprisingthe step of applying a thermally conductive film to the transferelement.
 9. A method according to claim 1, further comprising the stepof removing solvent and/or moisture from a region adjacent said transferelement during heating thereof.
 10. (canceled)
 11. An apparatus forprinting an image onto a 3-dimensional surface, the apparatuscomprising: at least one fixing device for fixing a transfer element,having an image printed thereon, in position relative to a 3-dimensionalsurface on which an image is to be printed and having a protectivecoating applied thereto; at least one heating device for heating thetransfer element to make it more flexible and to at least partiallytransfer the image into the protective coating; and at least oneapplication device for applying the flexible transfer element to thesurface with substantially uniform pressure across the area of contactbetween the transfer element and the surface such that the image facesthe surface.
 12. An apparatus according to claim 10, wherein at leastone said fixing device comprises at least one respective recess forreceiving at least one part having a respective 3-dimensional surface,and for fixing a respective transfer element relative to the or eachsaid part.
 13. An apparatus according to claim 11, wherein the recess isat least partially removable from a housing of the apparatus, and thecorresponding fixing device is adapted to fix the transfer element inresponse to insertion of the recess into the housing.
 14. An apparatusaccording to claim 12, further comprising at least one further fixingdevice, for holding the or each said recess in position in the housing.15. An apparatus according to claim 12, further comprising at least onecontrol device for actuating at least one said heating device and/or atleast one said application device in response to insertion of the recessinto the housing.
 16. An apparatus according to claim 10, wherein atleast one said heating device is adapted to direct hot gas towards thesurface.
 17. An apparatus according to claim 10, further comprising atleast one moisture and/or solvent removing device for removing solventand/or moisture from a region adjacent the transfer element.
 18. Anapparatus according to claim 10, wherein at least one said applicationdevice comprises a respective vacuum forming device.
 19. (canceled) 20.A transfer element adapted to have an image printed thereon, thetransfer element comprising: a carrier layer adapted to be heated tomake the carrier layer more flexible; an image supporting layer; and athermally conducting layer.
 21. (canceled)